Tensile specimens are subjected to dynamic testing at a high rate by attachment to and release from a testing machine through which an axial displacement is imposed on the specimen and diametrical displacement results, with both displacements being recorded. In the case of a notched cylindrical bar type of tensile specimen, cloverleaf shaped fixture grips are presently utilized for attachment to and removal of such specimens from the testing machine. Such fixture grips require complete assembly of parts during set up by means of four bolt fasteners and extensive fixturing by reason of which data recording errors are introduced during high rate dynamic testing operation because of fixture flexure. It is therefore an important object of the present invention to provide fixture grips for tensile specimen bars in dynamic test machine installations as aforementioned, which will decrease set up and removal time between tests to thereby increase the testing rate as well as to reduce flexure causing errors.